Hybrid porous cryogels processed using pressurized CO2 and freeze drying for life science applications

This work is aimed to present a novel route towards bimodal porous scaffolds for tissue engineering and regenerative medicine (TERM) applications. The key idea of the route is to produce highly porous hydrogels by gelation of alginate/biopolymer mixture under pressurized carbon dioxide in presence of calcium cations. Hybrid cryogels with gelatine, gellan gum, carboxymethylcellulose and lignin were successfully prepared after freeze drying. Cryogels for TERM are of special interest due to large and highly interconnected pores that provide non-constrained mass transfer for cell growth and proliferation. However, to achieve desirable mechanical properties as well as high adsorption capacity, bimodal meso and macroporous materials are greatly desirable. Two freezing regimes were studied in order to convert hydrogels into cryogels, namely slow freezing at –80° C and rapid freezing in liquid nitrogen.